Characterization of the different sound sources within the soundscape of coastline reef habitats (Bora Bora, French Polynesia)

Abstract

Marine habitats are characterized by different underwater soundscapes, composed of varying sources of anthropogenic, biological, and geological sounds. Passive acoustic monitoring (PAM) is now largely used to monitor marine habitats health and their possible changes through time. The present study aimed to describe five different habitats along the coastline of Bora Bora Island and characterized their soundscapes with a particular focus on the number and types of sound sources present. Acoustic recordings and visual surveys of fish communities were conducted from February to April 2021, (1) at a sandy beach, (2) near a grass zone, (3) in a mangrove, (4) near a trees zone (mainly composed of coconut trees), and (5) at the bottom of a road embankment every two weeks. Kaleidoscope Pro software allows to assign sound events to one of the following four categories: biological, anthropogenic, geological, and unidentified sounds. Our results showed that each coastal habitat had its own acoustic signature and habitat-specific fish communities. For example, the sandy beach had the highest fish density and species richness, as well as to the highest number of biological sound events during the day. However, this habitat was also the most acoustically polluted habitat due to a more significant tourism activity. At night, all habitats showed common characteristics both in biological composition and acoustic events, with a strong decrease in anthropogenic sources compared to the daytime. Our results suggest thus that PAM can be an effective tool to identify potential noise pollution for the conservation of coastline habitats in coral reefs.